For a long time, sheets of aluminum, silver and other metals have been used as heat-insulation materials to intercept radiant heat. More recently, so-called metallized plastic film which is obtained by depositing aluminum, zinc, silver or some other metal in the form of a thin layer by means of vacuum evaporation or plating on one surface of a transparent plastic film such as polyvinyl chloride or polyethylene terephthalate has also been used as a heat-insulation material. For effective use, the metallized plastic film is so positioned that the transparent plastic side of the film will face the radiant heat source. Thus, the mirror face of the metal layer reflects the radiant heat to provide the desired insulation.
With the sheet of metal or the metallized plastic film, the insulation is accomplished by causing the radiant heat to be reflected by the mirror face of metal layer as described above. When a building has an exterior surface covered with the sheet of metal or the metallized plastic film, for example, the solar ray impinging upon the mirror face of metal layer of the heat-insulation material is reflected and the reflected ray may have a dazzling effect on persons travelling persons travelling nearby. When the same heat-insulation material is used to cover an interior wall surface of a building, there has a disadvantage that the reflected ray tends to impart a feeling of aggravated fatigue to the occupants of the building.